How to view payload of a downloaded file

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Hey everyone, I started sniffing and downloaded a video from the internet and saved it as a PCAP file. I am trying to analyze the payload to determine what each hex data actually does in reference to the video. I've used FTK imager to get the original hex data of the video as I was the creator of it, however, none of the hex data for the video match the hex data I've found on the payload portion of the PCAP file. Does anyone have any advice or solutions as to why this is?